Method of using a cervical orthosis

ABSTRACT

A cervical orthosis is provided which supports the weight of the head with a chin support having a pair of transverse members extending rearward from the chin support to the wearer&#39;s shoulder. The transverse members are joined at the shoulder to a pair of vertical members which travel down the wearer&#39;s back. The orthosis is secured to the wearer a belt attached to the lower ends of the transverse member which is fastened about the wearer&#39;s torso. In a preferred embodiment the orthosis is formed of one continuous piece of a suitably rigid material and conforms to the contours of the wearer&#39;s body. A method of forming a customized orthosis to conform to the contours of a wearer positioned in a desired posture is also provided. An embodiment which is preferable for production by vacuum forming is disclosed. A method of using the apparatus for incrementally adjusting the position of a patient&#39;s head or the curvature of a patient&#39;s spine is disclosed.

This invention was made with government support under Grant No. BCS8908104 awarded by the National Science Foundation. The government hascertain rights in this invention.

This invention is a continuation-in-part of U.S. patent application Ser.No. 07/990,160 filed Dec. 14, 1992, now U.S. Pat. No. 5,320,596.

BACKGROUND OF THE INVENTION

This invention relates to cervical orthopedic devices. Moreparticularly, the invention relates to rigid devices for supporting theweight of the head through application of a supporting force by asupporting member in contact with the underside of the chin, and todevices for the control of cervical flexion, cervical extension, andcervical rotation, as well as kyphotic back.

It is sometimes necessary to restrict the range of motion of a patient'shead, or to support the weight of a patient's head using orthotic means.This is typically accomplished by encircling the neck with a semi-rigidcollar which supports the head while restricting or preventing cervicalflexion, extension, and rotation. When securely fixed about the neck,such collars form chin supporting surface beneath the chin upon whichthe weight of the head is rested. Such a device is disclosed, forexample, in U.S. Pat. Nos. 3,756,226 to Calabrese, and 5,038,759 toMorgenstern. It is sometimes necessary to use the collar in combinationwith a larger stabilizing device which is fastened about the chest andto which the collar is fixed to form a load-bearing member between thecollar and the chest. Such a device is disclosed, for example, in U.S.Pat. No. 4,502,471 to Owens.

Cervical collars have inherent disadvantages to the wearer. Collarsgenerally have a large surface area in contact with the skin, resultingin the undesirable trapping of perspiration and retention of body heatwhich cause discomfort to the wearers. Collars are also bulky and cannotbe worn beneath clothing. In addition, cervical collars are typicallyconstructed of semi-rigid materials which are not sufficiently resilientto retain their shape for more than several days of continuous use, andoften are not stiff enough to provide full support even in the course ofnormal use.

Stabilizers, which are designed to transfer the entire weight of thehead directly from the chin through the collar to the chest, may beawkward and uncomfortable for some wearers because they impinge directlyon the wearer's chest. In addition, stabilizers may not fit or stabilizeother patients with certain physical characteristics such as kyphosis.

Additionally, collars by their design are effective only as barriers tocervical flexion and extension. Consequently, they are inadequate forproviding proper positioning of the head for wearers whose problemsresult from improper positioning of the thoracic spine. For example, acervical collar is not effective to provide proper positioning for awheelchair-bound patient who tends to slump forward in his chair. In asimilar sense, collars are unable to compensate for other abnormalforward curvature of the upper spine such as kyphosis.

It is therefore the object of this invention to provide a cervicalorthosis which avoids use of the chest as a load bearing surface, whichimproves wearer comfort through minimization of surface area of thedevice in contact with the skin, which may be worn beneath clothing withminimal cosmetic effects to the wearer, which avoids the creation ofuncomfortable load bearing pressure points, and which further may beemployed to control the position of the head when such requires arepositioning of the forward curvature of the thoracic spine. It is afurther object of this invention to provide a cervical orthosis whichwill function effectively irrespective of the presence of kyphosis.

In addition, this invention is intended to be easily fabricated throughseveral different well-known fabrication methods; to be producable inone piece or in several pieces; to be customizable to the needs ofindividual wearers; and to be adjustable in its overall shape to effector to allow for changes in a wearer's body.

SUMMARY OF THE INVENTION

The present invention is a rigid cervical orthosis which distributes theforce from the weight of the head to the shoulders and the loweranterior torso through lever action pivoted at the shoulder. The deviceis preferably constructed of a moldable material and formed in a singlepiece which has a chin support having a pair of rigid transverse membersextending rearward along the wearer's lower jaw and neck to theshoulder. The transverse members join vertical members at the shoulderwhich extend for a predetermined distance down the length of the back.At the lower ends of the vertical members a belt is provided to befastened around the wearer's torso. In this manner downward force fromthe weight of the head is rested on the chin support, pivoted about theshoulders, and ultimately transferred to the lower anterior torso by theinward pull of the belt means. An additional element may be added to theorthosis to limit cervical extension. The device may be produced instandard sizes, which may be worn as fabricated or may be subsequentlycustom fitted to the individual wearer. The device may also be createdfrom a mold of the patient's body such that a custom made orthosis isprovided. For patients with sufficient flexibility, the orthosis may befurther designed to correct for kyphosis by molding the orthosis suchthat when in use it will reposition the thoracic spine to cause thewearer to conform to a desired posture. Alternatively, the orthosis maybe designed to conform to such curvature while maintaining itseffectiveness in supporting the head.

The orthosis may be fabricated in separate pieces which are later sizedto an individual patient and joined to constitute a whole apparatus. Thepieces may be chosen so as to facilitate their fabrication by well-knownmass production methods such as vacuum forming, rubber casting, orinjection molding. The apparatus may also be formed of materials whichallow for adjustment of the overall shape of the apparatus to effect orrespond to changes in the shape of the patient's body.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purpose of illustrating the invention, there are shown in thedrawings several possible embodiments of the invention including apreferred embodiment; however, the invention is not limited to theprecise embodiments shown.

FIG. 1 is a free body diagram showing the forces resulting from theweight of the head which are transmitted to the body of an individualwearing the disclosed orthosis.

FIG. 2 is a perspective view of the embodiment of FIG. 5 which includesa belt with a VELCRO fastening apparatus shown in a partially unfastenedconfiguration.

FIG. 3 is an overhead view of the device showing the chin supportsurface.

FIG. 4 is a rear view of an embodiment of the invention having twovertical members joined by a pair of joining members.

FIG. 5 is a rear view of an embodiment of the invention having twovertical members joined by a single broad joining member.

FIG. 6 is a rear view of an embodiment of the invention having a pair ofvertical members and a single continuous belt means.

FIG. 7 is a rear view of an embodiment of the invention having a pair ofvertical members joined by two flexible joining members.

FIG. 8 shows an embodiment of the invention orthosis designed to conformto the features of a patient with an abnormal forward curvature of theupper spine.

FIG. 9 shows an embodiment of the invention designed especially forproduction by vacuum forming.

FIG. 10 shows the upper piece of a two-piece embodiment of theinvention.

FIG. 11 shows the back piece of a two-piece embodiment of the invention.

FIG. 12 shows a cross-section of the joint formed by the transversemembers of the pieces shown in FIGS. 10 and 11.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

Referring to the drawings in detail, FIG. 1 shows the forces F_(S) andF_(B) born at the wearer's shoulder 4 and lower anterior torso 2,respectively, which result from support of the weight W_(H) of the head1 by the cervical orthosis 60. The weight W_(H) of the head 1 is born ata chin supporting surface 11 on a chin support 10 from which extends atransverse member 20. The transverse member 20 has a horizontal length Xwhich is approximately equal to the fixed distance between the wearer'schin 3 and the pivot point 12 near the top of the wearer's shoulder 4.The transverse member 20 is joined to a vertical member 30 of verticallength Y which extends down the wearer's back 5 from the transversemember at the pivot point 12. The wearer will bear a force F_(S) at thepivot point 12 as a result of the weight of the head 1 being pivotedabout the shoulder 4. The vertical member at its lower end 33 isprovided with a belt means 40 which transfers a resultant force F_(B) tothe wearer's lower anterior torso 2 at a belt contact area 8, which liesbetween the wearer's ribs and waist line.

The relative lengths of the transverse and vertical members aredeterminative of the forces born by the body at both the pivot point atthe shoulder and at the wearer's lower anterior torso. In designing anorthosis for a particular patient, the length of the transverse memberwill be a fixed distance, and therefore the length of the verticalmember will determine the relative magnitudes of forces F_(S) and F_(B).The angle of the force born by the shoulder is represented as θ in FIG.1.

Summing the forces, it is found that F_(S) =W_(H) /sinθ, F_(B) =W_(H)/tanθ, and Y/X=tanθ. It is desirable to minimize both F_(S) and F_(B) ;however, it is also necessary that length Y not be so great as toconstrain movement in the area 6 of the lumbar vertebra. In addition,since human skin cannot comfortably bear continuous pressures greaterthan about 3 psi and may suffer breakdown at higher pressures, theminimum contact areas necessary to comfortably distribute the forces atthe wearer's chin, shoulder and lower anterior torso are an equallyimportant consideration. It is of course desirable to minimize thoseareas of contact by minimizing the forces born at those areas. AssumingW_(H) =15 lbs and a maximum bearable pressure of 3 psi, and treating Xas a fixed distance, it is shown in Table 1 that an optimal balance ofthe several foregoing considerations is achieved where θ isapproximately 60 degrees, and length Y is approximately 1.7 times lengthX. Using the above equations, it can be seen that θ and length Y may bevaried to provide optimal fit and comfort to the individual wearer.

                  TABLE 1                                                         ______________________________________                                        Angle of Impingement of F.sub.S and Resulting Forces                          and Minimum Areas of Contact at Each Surface                                  θ                                                                            F.sub.s in lbf                                                                          F.sub.B in lbf                                                                          Y/X   A.sub.S in in.sup.2                                                                   A.sub.B in in.sup.2                    ______________________________________                                        30   30.0      26.0      0.6   10.0    8.7                                    45   21.2      15.0      1.0   7.1     5.0                                    50   19.6      12.6      1.2   6.5     4.2                                    55   18.3      10.5      1.4   6.1     3.5                                    58   17.7      9.4       1.6   5.9     3.1                                    59   17.5      9.0       1.7   5.8     3.0                                    60   17.3      8.7       1.7   5.8     2.9                                    61   17.2      8.3       1.8   5.7     2.8                                    62   17.0      8.0       1.9   5.7     2.7                                    65   16.6      7.0       2.2   5.5     2.3                                    70   16.0      5.5       2.8   5.3     1.8                                    ______________________________________                                    

FIGS. 2 and 3 illustrate a preferred embodiment of the invention, inwhich a chin support 10 is provided which has a chin supporting surface11. The chin supporting surface is shaped to conform generally to theshape of the underside of the wearer's chin, and the chin support iscupped to keep the chin seated on the chin supporting surface, therebypreventing cervical rotation when the orthosis is in place. A pair ofrigid transverse members 21 and 22 extends rearward from the chinsupport. For aesthetic purposes, the transverse members are preferablyas narrow and thin as the material they are constructed of will allow.FIG. 2 shows a pair of transverse members which are thin and flat. Themembers begin at the chin support and extend rearward along the lengthof the lower jaw and beyond the neck to the shoulders, with theirbroader surfaces formed such that they conform generally to the contoursof the wearer's lower jaw, neck, and shoulders.

At a point along the length of the transverse members 31 and 32, acervical extension control means 14 is provided. The control means isfixed at its ends 15 and 16 to the transverse members 31 and 32. When inuse, the control means extends about the back of the wearer's head,thereby limiting the wearer's degree of cervical extension. The controlmeans 14 may be of a flexible, semirigid, or rigid material, and isdetachably affixed to the transverse members 31 and 32 by any of severalwell known devices such as snaps or the like.

At the wearer's shoulders the transverse members 21 and 22 are joined tovertical members 31 and 32 which extend downward along the length of thewearer's back. At the lower ends 34 and 35 of the vertical members abelt 40 is provided which is of sufficient length to be fastenable aboutthe wearer's torso. The belt may be of a rigid, semirigid, or flexiblematerial. In the preferred embodiment, the belt comprises a pair ofjoinable nylon belt segments 41 and 42 fixed to lower ends 34 and 35respectively. The belt segments are fastened at their terminal ends 44and 45 to the lower ends of the vertical members by rivets 43 or othersecure fastening means. Other equivalent belts such as a belt comprisinga single continuous piece may be similarly employed. The belt isillustrated in FIG. 6.

Belt segments 41 and 42 are joinable at their joinable ends 46 and 47 bya secure fastening means 48 in which one belt segment 41 terminates in ametal ring 49, and the opposing belt segment 42 is provided with matingVELCRO fastening apparatus pieces 50 and 51 such that it may be passedthrough the metal ring and folded back upon itself and thereby secured.Other secure fastening means such as buckles, snaps, buttons or hooksmay be similarly employed. Once the belt is fastened, the orthosis issecured on the wearer, and the belt provides for static distribution ofthe load produced by the weight of the head between the shoulder andlower anterior torso.

The vertical members 31 and 32 which extend down the back may beunconnected, as illustrated in FIG. 6, or may be joined at a point belowthe shoulder by a joining member 36, as illustrated in FIG.5. Aplurality of smaller joining members 37 and 38 may be employed to reduceskin contact and thereby improve wearer comfort, as in the preferredembodiment shown in FIG. 4. The vertical and joining members, like thetransverse members, are preferably as narrow and thin as possible toreduce weight and material costs. FIG. 4 shows joining members which arethin and flat, with their broad surfaces generally conforming to thecontours of the wearer's body. The joining members are employed toprevent undesirable spreading of the vertical members due to tighteningof the belt, and may be formed of the same rigid material as thetransverse and vertical members, as illustrated in FIG. 4, or of someother material of suitable strength and elasticity. FIG. 7 illustratesan equivalent embodiment in which the joining members are of a suitableflexible material.

In the preferred embodiment as illustrated in FIGS. 2, 3, and 4, thechin support, a pair of transverse members, and a pair of verticalmembers are formed of one continuous piece of a suitably rigid materialsuch as acrylic resin. A reinforcing compound such as graphite may beincorporated, as is well known in the art, to add strength to the chosenmaterial where needed. Material strength is most crucial in the vicinityof the pivot point 12 at the wearer's shoulder. When the orthosis isformed of a single continuous piece, it is essential that an opening isprovided between the transverse members at the shoulder area which issufficient to allow insertion of the wearer's head through the space andinto proper position. FIG. 3 shows a keyhole-like space 53 which islarge enough to allow passage of the wearer's head.

When in use the orthosis is in contact with the wearer's skin in severalareas, most notably the belt contact area 8 shown in FIG. 1, the chinsupporting surface 11 shown in FIG. 3, and the shoulder pivot surface 13shown in FIG. 2. The orthosis should be designed so the wearer is notsubjected to an uncomfortable amount of pressure at any of these points.Table 1 provides minimum contact surface areas A_(B) and A_(S) forvarious configurations of the orthosis. In the preferred embodiment asshown in FIG. 3, a thin lining 55 of a semi-rigid material such as foamrubber is provided between the orthosis and the skin to equalize thedistribution of pressure over the areas of contact.

The invention may be produced in predetermined sizes through many wellknown techniques including injection molding, rubber casting, and vacuumforming. FIG. 9 illustrates an embodiment of the invention which isdesigned specifically for fabrication by a single stage vacuum formingprocess.. In this embodiment the outer surface of the vertical membersis continuous with the inner surface of the chin support. In contrast,in the other illustrated embodiments such as that of FIG. 2, the outersurface of the vertical members is continuous with the outer surface atthe chin support. Bearing in mind that the vacuum forming processrequires formation from a single continuous sheet of material, it can beseen by comparison of FIGS. 2 and 9 how the embodiment of FIG. 9eliminates the need for providing a twist in the transverse members toachieve the shape of the embodiment of FIG. 2. While this twist couldnot be accomplished in a single stage vacuum forming process, a secondstage of the process may be provided in which the material is reheatedand twisted to achieve the shape of the embodiment of FIG. 2. Thecentral ridge 78 in the transverse members 21 and 22 of the embodimentshown in FIG. 9 is preferred because it compensates for the stiffnesswhich is lost through elimination of the twists in the transversemembers as described above.

The invention may also be formed in separate pieces for later sizing andassembly. FIGS. 10 and 11 show the back piece 70 and upper piece 72 ofan orthosis which has been formed in two separate standard sized pieces.Formation of the invention in this manner is advantageous because itsimplifies the molding process, and because the use of standard sizedpieces allows a single mold to be used to produce pieces which maysubsequently be custom-fitted for an individual wearer. For purposes ofcustomization, the back piece is provided with an extended lower end 74,and the upper piece is provided with extended transverse members 76. Thetransverse members of the back piece and upper piece are also providedwith a central ridge 78 for added stiffness. FIG. 12 shows across-section of a joint formed in a preferred embodiment by thetransverse members 80 of the back piece and the transverse members 76 ofthe upper piece. In this embodiment, the transverse members 76 and 80are provided with central ridges 78 which provide added stiffness. Thetransverse members 76 of the upper piece are additionally provided withalignment edges 82 which receive the transverse members of the backpiece and make the joint self-aligning.

There are many well-known methods by which the back piece and upperpiece may be joined. They may be bonded using a suitable adhesive or maybe fused using a suitable welding method. The members may additionallyor alternatively be joined by any suitable mechanical fastening means,such as a Chicago fastener 84, as shown in FIG. 12.

Customization is accomplished by measuring the chin-to-shoulder distanceof a prospective wearer and determining the optimal dimensions of thedevice for that wearer in accordance with Table 1, above. The lower end74 of the back piece and the transverse members 76 of the upper pieceare then trimmed to the proper lengths and are assembled as describedbelow. After the pieces are assembled, a belt is attached at the lowerend of the back piece. A layer of padding may be provided over the areaof the joint which will be in contact with the patient's body.

Custom-fitted embodiments of the invention may also be produced byforming the orthosis directly on a model of the wearer. The followingdescription is provided as one example of such a customizing process: Acotton stockinette is placed over the wearer to cover the area of thepatient between the nose and waist. The wearer is then positioned in aposture to which the model and the orthosis are desired to conform.Plaster bandage splints are placed about the wearer so that animpression is made of the wearer in the areas to which the orthosis isintended to conform. The impression is allowed to harden and is thenremoved from the wearer and filled with plaster to create a model of thewearer. The model is smoothed and sealed with a parting lacquer. To formthe orthosis, the model is covered with a polyvinyl-alcohol bag. This iscovered with 1/2 oz. dacron felt, and then with 12 layers of 623T3 nylonalternated with carbon graphite matting. A second PVA bag is placed overthe layup, which is then impregnated with carbonacrylic resin. After theresin has cured, trim lines are determined and the orthosis is removedfrom the model by breaking apart the model. The orthosis may besubsequently trimmed to the exact desired specifications, and thepadding and belt means added. In this manner a rigid orthosis may beproduced which functions effectively while conforming to the physicalcontours of the individual. As illustrated in FIG. 7, an orthosis 60 maybe produced which conforms to the features of a wearer with a kyphoticback 7.

This customizing technique is especially useful in designing an orthosiswhich will correct both exaggerated cervical flexion and thoracickyphosis in wearers who exhibit sufficient spinal flexibility. These mayinclude patients with kyphosis or patients who are wheelchair bound andtend to slump forward. Since the orthosis is rigid, the wearer's spinewill flex to conform to the contours of the orthosis when it is in placeon the wearer. Consequently, a device may be produced using the abovemodeling technique where the initial cast is taken of the wearer whilehe is positioned in a posture to which he intends the orthosis to causehim to conform. An individual wearing such an orthosis will assume thesame posture as that of the model from which the orthosis was cast.

Certain embodiments of this invention may also be produced which allowfor incremental repositioning of the head and back in patients whosecondition is the result of contracture which has led to a shortening ofthe flexion plane of the thoracic or cervical spine. In accordance withthis embodiment of the invention, an orthosis is formed to conform tothe curvature of the patient's back and to the angle of the patient'schin relative to the shoulders. The orthosis is formed of a plastic ofsuitable temperature and stiffness such that it may be heated andreshaped as needed. The angle of the chin support or the curvature ofthe vertical members is then incrementally adjusted over time so thatthe wearer is gradually repositioned to a desired posture. The time andincrements of adjustment will vary with the needs of the individualpatient.

What is claimed is:
 1. A method of controlling the position of the bodyof a patient in the area of the patient's head, neck, and spine,comprising the steps of:a) providing a cervical orthosis whichcomprises:a chin support having a chin supporting surface; at least onerigid transverse member extending rearward from said chin support, andbeing adapted to reach to and make contact with the wearer's shoulder;at least one rigid vertical member extending downward from the rearwardend of said transverse member; and a belt, capable of being securelyfastened about the torso of the wearer, disposed at the lower end ofsaid vertical member; and, b) placing said orthosis upon the body ofsaid patient such that said patient's chin rests upon said chin supportand said belt is fastened about said patient's torso, said orthosisthereby acting as a lever pivoted at said patient's shoulders.
 2. Themethod of claim 1, wherein the step of providing said orthosis comprisesthe steps of:a) positioning the patient in a predetermined posture towhich the orthosis is intended to conform; b) creating a cast of thecontours of at least the patient's back, shoulder, and lower jaw regionswhile the wearer is positioned in said desired posture; c) creating fromsaid cast a model of the contours of the body parts of the patient towhich the orthosis is intended to conform; d) forming a singlecontinuous piece of a rigid material around said model which conforms tothe contours of said model, said continuous piece of rigid materialcovering enough of said model to include the entirety of said orthosis;e) removing said continuous piece of rigid material from said model; andf) trimming said continuous piece of rigid material as necessary toyield said orthosis.
 3. The method of claim 1, wherein the step ofproviding said orthosis comprises the steps of:a) providing an upperpiece of said orthosis having a chin support and transverse members; b)providing a back piece of said orthosis having a vertical member andtransverse members; and c) joining said transverse members of said upperpiece to said transverse members of said back piece.
 4. The method ofclaim 1, wherein said orthosis is formed of a material of a suitabletemperature and stiffness, whereby said orthosis may be heated andreshaped.
 5. The method of claim 2, wherein said orthosis is formed of amaterial of a suitable temperature and stiffness, whereby said orthosismay be heated and reshaped.
 6. The method of claim 3, wherein saidorthosis is formed of a material of a suitable temperature andstiffness, whereby said orthosis may be heated and reshaped.
 7. Themethod of claim 4, comprising the further step of:increasing the anglebetween said vertical member and said transverse member in predeterminedincrements over time, thereby incrementally raising the position of saidpatient's head in relation to said patient's shoulders.
 8. The method ofclaim 4, comprising the further step of:adjusting the curvature of thevertical member in predetermined increments over time, therebyincrementally changing the curvature of the patient's spine.
 9. Themethod of claim 5, comprising the further step of:increasing the anglebetween said vertical member and said transverse member in predeterminedincrements over time, thereby incrementally raising the position of saidpatient's head in relation to said patient's shoulders.
 10. The methodof claim 5, comprising the further step of:adjusting the curvature ofthe vertical member in predetermined increments over time, therebyincrementally changing the curvature of the patient's spine.
 11. Themethod of claim 6, comprising the further step of:increasing the anglebetween said vertical member and said transverse member in predeterminedincrements over time, thereby incrementally raising the position of saidpatient's head in relation to said patient's shoulders.
 12. The methodof claim 6, comprising the further step of:adjusting the curvature ofthe vertical member in predetermined increments over time, therebyincrementally changing the curvature of the patient's spine.